Combustion apparatus



March 22, 1938. L. v. ANDREWS COMBUSTION APPARATUS Filed Oct. 4, '1933 L. VANDREWs Patented Mar. 22, 1938 UNITED STATES PATENT OFFICE Riley Stoker Corporation, Worcester, Mass,

a corporation of Massachusetts Application October 4, 1933, Serial No. 692,162

Claims. This invention relates to combustion apparatus, and more particularly to an apparatus suitable for burning pulverized fuel and oil either alone or simultaneously.

5 Que form of burner commonly utilized for burning pulverized fuel comprises a burner pipe arranged to discharge a jet of fuel and primary air through an openingin a furnace wall, the secondary air being introduced into the furnace in a stream annular in cross-section and surrounding the fuel jet. It has been proposed heretofore to mount an oil atomizing nozzle or gun inside of the fuel pipe in a burner of this type, but various difficulties have been encountered when burning oil alone with such an arrangement. Certain parts of the burner become overheated and hence require frequent replacement, and neither the capacity nor the combustion efficiency is so great as would ordinarily be expected from a burner designed for burning oil and having no provision for the burning of pulverized fuel.

It is accordingly one object of the invention to overcome these difficulties and to provide an apparatus which will burn pulverized fuel and oil, either alone or simultaneously, with high efficiency and at high combustion rates when desired.

I It is a further object of the invention to provide a combination oil and pulverized fuel burner and associated parts so constructed and arranged 7 that either fuel may be burned alone for long periods without damage to the burner.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto. In accordance with my invention I provide a burner having a pipe for the delivery of pulverized fuel to a furnace, and. means to introduce secondary air around the outside of the fuel jet. An oil atomizing nozzle is mounted within the pipe. The pipe is supplied with pulverized fuel through a conduit leading preferably from a suitable pulverizer. Manually operable valve means is provided whereby air can be admitted to the conduit when burning oil alone. In case the burner is of the forced draft type, this air may be withdrawn from the forced draft duct. Otherwise, the air may be admitted under the influence of the natural draft of the furnace. In a forced draft installation, the valve means is preferably arranged to prevent blowing of the high pressure air in a reverse direction through the pulverizer. i

Referring to the drawing illustrating one embodiment of the invention, and in which like reference numerals indicate like parts,

Fig. 1 is an elevation of combustion apparatus for burning pulverized fuel or oil under forced 6 draft, certain parts being shown in section;

Fig. 2 is an enlarged view on the line 2-2 of Fig. 1; and

Fig. 3 is a view similar to Fig. 1 but showin a natural draft installation.

The embodiment illustrated in Fig. 1 comprises a vertical furnace wall Ill having an opening I l therein which is preferably circular and flares outwardly toward the rear or furnace side of the wall. A horizontal cylindrical burner pipe 15 I2 is mounted in front of the opening H and arranged to discharge pulverized fuel rearwardly and centrally through the opening. This pipe 12 is connected by means of a conduit M to a pulverizer l5 which may be of any suitable type, 20 one particularly satisfactory apparatus being disclosed in the patent to Riley et al. No. 1,759,134,

At the rear or discharge end of the burner pipe I! I preferably mount a spreading device comprising a number of vanes H which extendradi- 5 ally across the path of the pulverized fuel stream. These vanes are arranged at an angle to the burner axis so that they deflect the fuel and throw it outwardly as it leaves the pipe l2. In the preferred construction the vanes l1 are 3 mounted on the rear end of a small tube l8 which is supported centrally within the pipe l2.

' Secondary air is introduced into the furnace through the opening Ii around the outside of the fuel stream. 20 forming an air chamber 2| located outside the wall l0 and communicating with the opening ll. Air is supplied to the chamber 2i through a forced draft duct 22 which is connected to a suitable forced draft fan (not shown). Dampers 40 24 serve to control the flow of air from the duct 22 to the chamber 2]. The air entering the opening I l is preferably given a. whirling motion about thev pipe I2 by means of vanes 25 mounted in the chamber 2|, these vanes being constructed and 45 arranged in the manner disclosed in the patent to Craig et al. No. 1,843,662.

In order that oil may be burned when desired, an oil atomizing nozzle or gun 26 is mounted within the tube l8 with its rear or discharge end 50 adjacent the rear end of the burner pipe l2. Oil is supplied to the nozzle 26 through a pipe 21. When pulverized fuel alone is to be burned, the oil nozzle 26 may be removed if desired.

.When burning oil alone with the apparatus as 55 For this purpose I provide walls 35 39. A second valve 3| is provided in the conduit- I 4 between the pulverizer l5 and the junction of the passage 29 with the conduit, this valve serving to prevent air from blowing back into the pulverizer when the latter is shut down. The valves and 3| are preferably of the quarterturn plug type, one suitable construction being disclosed in my prior Patent No. 1,849,395.

The operation of this embodiment will now be apparent from the above disclosure. When burning pulverized fuel, either alone or in combination with oil, valve 30 will be closed and valve 9| open. Pulverized fuel and primary air will flow from the pulverizer I6 through the conduit I 4 to the burner pipe I2, and the stream as it issues from the pipe will be deflected by the vanes l1 outwardly into the surrounding whirling stream of secondary air supplied from the chamber 2| and duct 22. When oil alone is to be burned, the pulverizer will be shut down, valve 3| will be closed, and valve 30 will be opened to allow air to flow from the duct 22 through the passage 29 to the burner pipe l2. This air will be deflected by the vanes l1 and hence will be whirlingrapidly as it strikes the atomized oil immediately after the latter leaves the nozzle 26. The air is thus mixed with the oil almost instantly, and the combustion is extremely rapid and efllcient. Moreover, the air flowing through the pipe l2 will cool this pipe and also the tube l8 and the vanes l'l, thus protecting these parts from overheating and ensuring a long life of service.

In Fig. 3 I have shown apparatus similar to that already described, but arranged for use in an installation having natural or induced draft. This embodiment comprises a furnace wall 96 having an opening 26 therein, and a burner pipe 31 in front of the opening to discharge pulverized fuel therethrough. The pipe 31 is connected by means of a conduit 39 to a pulverizer. Deflecting vanes 42 are mounted at the rear of the pipe 31, these vanes being mounted on a tube 43 supported centrally within the pipe. An oil atomizing nozzle 44 is mounted within the tube 43, and an oil supply pipe 45 is connected to the nozzle. Vanes 41 are arranged around the outside of the wall opening 36 to whirl the secondary air which enters the opening under the influence of the furnace draft or suction.

In order to admit air to the pipe 21 when burning oil alone, I provide a passage 49 which es tablishes communication between the conduit 39 and the atmosphere. The flow in this passage is controlled by a valve 50 similar to the valves 30 and 3|.

The operation of this embodiment is similar to that of the Fig. 1 arrangement. When burning pulverized fuel either alone or in combination with oil, valve 50 will be closed. when burning oil alone, the pulverizer will be shut down and valve 50 will be opened, thus allowing the furnace draft to draw air inwardly through the passage 49 and pipe 31. This air will cool the burner parts and aid in obtaining rapid and efficientcombustion of the oil. drawn inwardly through the opening furnace draft.

It will be apparent that the air can be introduced into the pipe 31 in the manner disclosed in Fig. 3 even though the secondary air be supplied under pressure, but in such cases I prefer to utilize the construction shown in Fig. 1.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. Combustion apparatus comprising a burner pipe adapted to discharge a jet of pulverized fuel and primary air, means .to supply secondary air around the outside of the fuel jet, means adjacent the discharge end of the pipe to deflect the issuing fuel outwardly into the secondary air, a fuel pulverizer arranged to supply the pulverized fuel and primary air, a conduit connecting the pulverizer with the burner pipe, an oil atomizing nozzle mounted within the burner pipe, a passage to supply air to the conduit at a point between the pulverizer and the burner pipe, and a valve to control the flow in the passage.

2. Combustion apparatus comprising a burner pipe adapted todischarge a jet of pulverized fuel and primary air, means to supply secondary air around the outside of the fuel jet, vanes adjacent the discharge end of the pipe and extending across the path of the fuel, said vanes being arranged at an angle to the burner pipe axis so that they deflect the fuel outwardly into the The secondary air is 36 by the secondary air, a fuel pulverizer arranged to supply the pulverized fuel and primary air, a conduit connecting the pulverizer with the burner pipe, an oil atomizing nozzle mounted within the burner pipe with its discharge end adjacent to said vanes, a passage to supply air to the conduit at a point between the pulverizer and the burner pipe, and a valve to control the flow in the passage.

3. Combustion apparatus comprising a burner pipe adapted to discharge a jet of pulverized fuel and primary air, means to' supply secondary air around the outside of the fuel jet, a tube mounted within the burner pipe, vanes mounted on the tube adjacent the discharge end of the pipe and extending radially across the path of the fuel, said vanes being arranged at an angle to the burner axis so that they deflect the fuel outwardly into the secondary air, a fuel pulverizer arranged to supply the pulverized fuel and primary air, a conduit connecting the pulverizer with the burner pipe, an oil atomizing nozzle mounted within the tube with its discharge end adjacent to said vanes, a passage to supply air to the conduit at a point between the pulverizer and the burner pipe, and a valve to control the flow in the passage.

4. Combustion apparatus comprising a burner pipe adapted to discharge a jet of pulverized fuel and primary air, means including a forced draft ductto supply secondary air around the outside of the fuel jet, means adjacent the discharge end of the pipe to deflect the issuing fuel outwardly into the secondary air, a fuel pulverizer arranged to supply the pulverized fuel and primary air, a conduit connecting the pulverizer with the burner pipe, an oil atcmizing nozzle mounted within the burner pipe, a passage connecting the forced draft duct with the conduit at a point between the pulverizer and the burner pipe, and a valve to control the flow in the passage.

5. Combustion apparatus comprising a burner -.ized fuel and primary air,

pipe adapted to discharge a jet of pulverized fuel and primary air, means to supply secondary air around the outside of the fuel Jet, means adjacent the discharge end of the pipe to deflect the issuing fuel outwardly into the secondary air, a fuel pulverizer arranged to supply the pulvera conduit connecting izing nozzle mounted within the burner pipe, and valve controlled means to admit air directly from the atmosphere into said conduit at a point between the pulverizer and the burner pipe.

L. v. ANDREWS.

the pulverizer with the burner pipe, an oil atom- 

